1. Field of the Invention
This invention relates to placing an additional grounding strip on an electrical connector so that at the time a connection is made, currents resulting from electrostatic discharge events (ESD) will be properly grounded.
2. Description of Related Art
The potential harmful effects to electrical components resulting from ESD are well known. To minimize these effects, buyers of electrical connectors frequently require that these connectors have grounding protection and that this protection meet certain tests. By way of example, Bellcore has specific tests that D-Sub connectors must pass in order to be qualified for use (i.e., TR-NWT-001089 Sect. 2.3, ESD Test Methods). Such D-SUB connectors typically have a ground plane over the pin openings (e.g., ITT CANNON 9334 DBM53513-1792 25-pins female D-SUB) to eliminate or reduce ESD problems during ESD qualification of the connectors. The ground plane on the D-SUB connector is intended for attracting the ESD and directing the harmful discharge current to ground so that there will be no ESD exposure to components on boards on which the connector is mounted.
As this grounding plane is frequently insufficient to meet the testing requirements, additional grounding methods have been employed. One such method is to use a grounded metal foil to attract the ESD events. As depicted in FIG. 1 the ground plane for the ITT CANNON connector is made of a metal foil with openings (cut-out holes) to match those on the connector. When placing the metal foil over the pin openings of the connector, the openings on the metal foil must be aligned perfectly with those on the connector to insure that the connector will mate properly (otherwise, there will be shorts between the pins and the ground). Because of this reliability concern, other costly techniques have also been investigated to improve reliability when modifying the D-SUB connectors to meet the Bellcore ESD requirements.
One such technique employs using a metal coating to attract ESD events. As depicted in FIG. 2 this technique is to paint a thin metal coating over the whole surface of the pin opening of the connector (e.g., CINCH connector). The problem with the painting technique is that the integrity of the thin coating, placed over the pin openings of the connector, can not be visually inspected and verified. Thus, it is extremely expensive to make D-SUB connectors that can meet the Bellcore ESD requirements. Further, many vendors do not even attempt to meet strict ESD testing requirements, such as those imposed by Bellcore, because of the reliability concerns regarding the use of a ground plane over the pin openings.
The present invention employs a new method for eliminating or reducing ESD on connectors. This method uses a much simpler ground plane (a strip line) that can be placed between the rows of the pin openings of the connector to eliminate ESD while maintaining high reliability.
These and other features of the invention will be more fully understood by reference to the following drawings.